The latest cuts are likely an effort to reach annual sales goals, which is 12,000 Prius' sold for 2013. For the first nine months, Toyota has only sold 8,000.

Many other automakers have been lowering prices this year, such as General Motors, which cut the Volt's price by $5,000 to $34,995; Ford, which cut the price of the Focus EV by $4,000 to $35,200, and Nissan, which slashed the Leaf's price by 18 percent earlier this year to $28,800 (and has seen a significant sales increase since).

Earlier this month, Toyota said it would pass on electric vehicles to focus more heavily on hydrogen fuel cell technology and continue releasing hybrid vehicles. For instance, the automaker said it would release 15 new hybrids and unveil its first hydrogen fuel cell vehicle by 2015.

Toyota is focused on its next-generation Prius as well, which is expected to have better batteries with higher energy density. The company said it's using nickel-metal hydride and lithium-ion where necessary and even upped its research on new battery technologies like solid state and lithium air as well as magnesium. The Prius will also feature smaller electric motors; thermal efficiency of the gasoline engine will be boosted from 38.5 percent in current models to 40 percent in the next-generation; the use of Toyota New Global Architecture (TNGA) will allow for a lower center of gravity and increased structural rigidity, and better aerodynamics will offer an all-new exterior design.

One of the problems with charging at night is that transformers generate internal heat proportional to current delivered, and much of that heat dissipates overnight, when both the sun is down (reducing external thermal input), and when there is low energy usage. Lots of overnight charging combined with a heat spell could induce a higher rate of transformer failure, particularly in the neighborhoods. Central transformers quite often have active cooling and are less susceptible to this problem.